The Thunder defeated the Mavericks 121-116 on Saturday night to clinch a postseason berth.
Oklahoma City ended a nine-game losing streak at Dallas, dating back to their time in Seattle.
"It's a great feeling, but I've been impressed with our guys' work ethic all year long and I know that's not going to change," coach Scott Brooks said.
The Thunder's young players didn't do any postgame celebrating because they have a home game against the Timberwolves on Sunday.
"It's cool to celebrate after the game but we've got a quick turnaround ... so we've got to come out there and produce," Durant said. "Maybe on our day off we'll celebrate."